(Singular-Coccus = Gr. Kokkos = Berry, rounded). They are spherical arid according to cell arrangement they are: Solitary (single) (Monococcus), in a pair (Diplococci), in the chain (Streptococci), in a cluster (Staphylococci), etc. They are non-flagellated.
(Singular-Bacillus = L, Bakulus = A-rod). They are rod-shaped. They may be found in pairs (Diplobacillus) or in chains (Streptobacillus) etc. They may be flagellated.
(Singular-Spirillum = Gr. Sperira = A-coil. They are spiral or corkscrew-shaped (spirillum).